The invention relates to an apparatus for cleaning alternatively and at will two or more neighbouring cylinders in a printing machine, by means of a single cleaning device.
Examples of such equipment are described in U.S. Pat. No. 5,408,930 (Loos) and U.S. Pat. No. 5,479,857 (Braun) where the cleaning apparatus can rotate about an axis parallel to the presser which can thus be oriented alternatively against either of two parallel neighbouring cylinders inside the printing machine. Once the presser is correctly oriented relative to a cylinder, it is deformed elastically and/or pushed towards that cylinder so as to touch it with the cloth, which is soaked with the cleansing fluids. These devices are not designed to also operate on cylinders in which there are gaps on the surface, containing for example clamps, as for instance in plate cylinders, in which the cleaning cloth could interfere with the said clamps and be torn. Also known is the device disclosed in PCT patent application WO 00/34045 in the name of the present applicants, where the cleaning device is supported by means which on command enable it to perform a rotary or pivoting movement about an axis, possibly represented by an actual shaft, that is parallel to and located between the two cylinders to be cleaned, while other means cause the same cleaning device to perform a simultaneous rotary or pivoting movement about their own longitudinal axis which passes through the points of attachment to the said supporting means. This device, unlike the US patent devices mentioned above, includes a component of displacement perpendicular to the cylinder that is to be cleaned, and this component is made use of to ensure that the device can automatically avoid interference between the cleaning cloth and the clamps of a plate cylinder. To this end the cleaning device is provided on at least one end with an idle roller able to engage with at least one cam mounted at the side of the plate cylinder, across the gap containing the clamps. When the roller encounters this cam, the cleaning device automatically backs away from the cylinder it is cleaning, thus avoiding interfering with the clamps, and once the cam has been passed, the said cleaning device moves back into contact with the cylinder under the elastic force exerted by the pneumatic actuators by which the movement of the device is controlled.
The above device presupposes the existence between the cylinders to be cleaned, and parallel with these cylinders, of a shaft which the device uses as a fulcrum means. For cases where no such shaft exists, the same applicants devised an apparatus disclosed in European patent application No. 01 11 2119.1 filed May 17, 2001 which exploits the cleaning device itself as a torsion bar and provides a rack-and-pinion mechanism. This apparatus preserves the advantage of the automatic backing away from the clamps of the plate cylinder, as in the previous apparatus, but takes up an excessive amount of space transversely because the means by which the cleaning device is guided and moved are all located at the opposing ends of the device and greatly increase the length or width of the entire apparatus. This apparatus is therefore suitable for printing machines in which the ends of the cylinders are sufficiently distant from the side walls of the machine frame in which they are supported or in all those cases where the printing plate occupies only part of the length or breadth of the cylinder carrying it.
The invention relates to an apparatus that performs the same functions as the apparatuses disclosed in the Italian patent application indicated above, but unlike these can be mounted on printing machines that have no shaft mounted parallel to and located between the cylinders that are to be cleaned and in which the ends of the cylinders are at perhaps only a short distance from the supporting side walls, or even where the printing plates occupy almost the whole length or breadth of their cylinder, the said apparatus having only very small fittings added to the ends of the cleaning device. According to the invention, the cleaning device is mounted via its ends on shoulders that pivot on a pair of parallel arms, these arms being hinged at their other end to the machine side walls and connected to each other by a robust torsion bar. The said shoulders are provided, at an exact distance from the point where they hinge on the said arms, with rollers that follow the profile of linear cams mounted on the said machine side walls, while at a point at approximately one hundred and eighty degrees away from the said rollers, at least one of the shoulders pivots on the rod of a linear assembly of pneumatic actuators, which assembly pivots at the other end on a point of the arm close to the point where the latter pivots on its respective machine side wall. By means of the assembly of pneumatic actuators and of the said linear cams, the cleaning device can be oriented at will against either of these cylinders to be cleaned or can be set in a position remote from both the cylinders, this position being useful as a rest position and a position for maintenance of the apparatus. Mounted on at least one of the said arms, in an intermediate position, is an idle roller designed to engage with a corresponding cam situated at the end of the plate cylinder, across the gap containing the clamps, so that the cleaning device is automatically moved away whenever it passes over the said clamps, thus preventing any interference with these.